Diff: cmsis_dsp/BasicMathFunctions/arm_shift_q7.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/BasicMathFunctions/arm_shift_q7.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,215 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_shift_q7.c    
+*    
+* Description:    Processing function for the Q7 Shifting    
+*    
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*  
+* Version 1.1.0 2012/02/15 
+*    Updated with more optimizations, bug fixes and minor API changes.  
+*   
+* Version 1.0.10 2011/7/15  
+*    Big Endian support added and Merged M0 and M3/M4 Source code.   
+*    
+* Version 1.0.3 2010/11/29   
+*    Re-organized the CMSIS folders and updated documentation.    
+*     
+* Version 1.0.2 2010/11/11    
+*    Documentation updated.     
+*    
+* Version 1.0.1 2010/10/05     
+*    Production release and review comments incorporated.    
+*    
+* Version 1.0.0 2010/09/20     
+*    Production release and review comments incorporated.    
+*    
+* Version 0.0.7  2010/06/10     
+*    Misra-C changes done    
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**        
+ * @ingroup groupMath        
+ */
+
+/**        
+ * @addtogroup shift        
+ * @{        
+ */
+
+
+/**        
+ * @brief  Shifts the elements of a Q7 vector a specified number of bits.        
+ * @param[in]  *pSrc points to the input vector        
+ * @param[in]  shiftBits number of bits to shift.  A positive value shifts left; a negative value shifts right.        
+ * @param[out]  *pDst points to the output vector        
+ * @param[in]  blockSize number of samples in the vector        
+ * @return none.        
+ *    
+ * \par Conditions for optimum performance    
+ *  Input and output buffers should be aligned by 32-bit    
+ *    
+ *        
+ * <b>Scaling and Overflow Behavior:</b>        
+ * \par        
+ * The function uses saturating arithmetic.        
+ * Results outside of the allowable Q7 range [0x8 0x7F] will be saturated.        
+ */
+
+void arm_shift_q7(
+  q7_t * pSrc,
+  int8_t shiftBits,
+  q7_t * pDst,
+  uint32_t blockSize)
+{
+  uint32_t blkCnt;                               /* loop counter */
+  uint8_t sign;                                  /* Sign of shiftBits */
+
+#ifndef ARM_MATH_CM0
+
+/* Run the below code for Cortex-M4 and Cortex-M3 */
+  q7_t in1;                                      /* Input value1 */
+  q7_t in2;                                      /* Input value2 */
+  q7_t in3;                                      /* Input value3 */
+  q7_t in4;                                      /* Input value4 */
+
+
+  /*loop Unrolling */
+  blkCnt = blockSize >> 2u;
+
+  /* Getting the sign of shiftBits */
+  sign = (shiftBits & 0x80);
+
+  /* If the shift value is positive then do right shift else left shift */
+  if(sign == 0u)
+  {
+    /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
+     ** a second loop below computes the remaining 1 to 3 samples. */
+    while(blkCnt > 0u)
+    {
+      /* C = A << shiftBits */
+      /* Read 4 inputs */
+      in1 = *pSrc;
+      in2 = *(pSrc + 1);
+      in3 = *(pSrc + 2);
+      in4 = *(pSrc + 3);
+
+      /* Store the Shifted result in the destination buffer in single cycle by packing the outputs */
+      *__SIMD32(pDst)++ = __PACKq7(__SSAT((in1 << shiftBits), 8),
+                                   __SSAT((in2 << shiftBits), 8),
+                                   __SSAT((in3 << shiftBits), 8),
+                                   __SSAT((in4 << shiftBits), 8));
+      /* Update source pointer to process next sampels */
+      pSrc += 4u;
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+
+    /* If the blockSize is not a multiple of 4, compute any remaining output samples here.        
+     ** No loop unrolling is used. */
+    blkCnt = blockSize % 0x4u;
+
+    while(blkCnt > 0u)
+    {
+      /* C = A << shiftBits */
+      /* Shift the input and then store the result in the destination buffer. */
+      *pDst++ = (q7_t) __SSAT((*pSrc++ << shiftBits), 8);
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+  }
+  else
+  {
+    shiftBits = -shiftBits;
+    /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
+     ** a second loop below computes the remaining 1 to 3 samples. */
+    while(blkCnt > 0u)
+    {
+      /* C = A >> shiftBits */
+      /* Read 4 inputs */
+      in1 = *pSrc;
+      in2 = *(pSrc + 1);
+      in3 = *(pSrc + 2);
+      in4 = *(pSrc + 3);
+
+      /* Store the Shifted result in the destination buffer in single cycle by packing the outputs */
+      *__SIMD32(pDst)++ = __PACKq7((in1 >> shiftBits), (in2 >> shiftBits),
+                                   (in3 >> shiftBits), (in4 >> shiftBits));
+
+
+      pSrc += 4u;
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+
+    /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
+     ** No loop unrolling is used. */
+    blkCnt = blockSize % 0x4u;
+
+    while(blkCnt > 0u)
+    {
+      /* C = A >> shiftBits */
+      /* Shift the input and then store the result in the destination buffer. */
+      in1 = *pSrc++;
+      *pDst++ = (in1 >> shiftBits);
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+  }
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+
+  /* Getting the sign of shiftBits */
+  sign = (shiftBits & 0x80);
+
+  /* If the shift value is positive then do right shift else left shift */
+  if(sign == 0u)
+  {
+    /* Initialize blkCnt with number of samples */
+    blkCnt = blockSize;
+
+    while(blkCnt > 0u)
+    {
+      /* C = A << shiftBits */
+      /* Shift the input and then store the result in the destination buffer. */
+      *pDst++ = (q7_t) __SSAT(((q15_t) * pSrc++ << shiftBits), 8);
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+  }
+  else
+  {
+    /* Initialize blkCnt with number of samples */
+    blkCnt = blockSize;
+
+    while(blkCnt > 0u)
+    {
+      /* C = A >> shiftBits */
+      /* Shift the input and then store the result in the destination buffer. */
+      *pDst++ = (*pSrc++ >> -shiftBits);
+
+      /* Decrement the loop counter */
+      blkCnt--;
+    }
+  }
+
+#endif /* #ifndef ARM_MATH_CM0 */
+}
+
+/**        
+ * @} end of shift group        
+ */